PROJECT SUMMARY/ABSTRACT The research in this proposal focuses on plant immune perception of bacterial pathogens. Plants possess a sophisticated innate immune system comprised of germline encoded immune receptors capable of recognizing all pathogen classes. These immune receptors are structurally similar to their animal counterparts and include surface localized pattern recognition receptors (PRRs) as well as intracellular nucleotide-binding leucine rich repeat (NLR) receptors. Plant immune receptors and downstream signaling nodes are controlled by post- translational modifications, allowing rapid regulation of the initiation, amplitude, and duration of defense. Although PRRs and NLRs are structurally distinct and exhibit differences in defense timing and amplitude, they share significant overlap in posttranslational modification of critical downstream signaling nodes. However, our data demonstrates that the kinases involved in mediating PRR and NLR responses at key signaling nodes are distinct. Here, we will investigate mechanisms regulating innate immune signal intensity, signal propagation and cell specific responses within a leaf. We will analyze the importance of specific protein kinases for mediating the intensity of NLR-triggered immune responses. We will investigate the role of tandemly arrayed cysteine rich-receptor like kinases as secondary immune receptors that propagate signals of pathogen perception. Finally, we will investigate cell specific innate immune responses. This project will train the next generation of scientists and result in discoveries that lead to a better understanding of how signals of initial pathogen perception are integrated into an effective defense response within a plant organ.